I have finished the beverage antenna preamplifier. The 9:1 transformer is based on the W8JI’s recommodations. It is wound on the tree binocular ferrite cores BN73-202. I was wondering how the SWR is. When terminated with 450 ohms there is no significiant return power, when terminated with 470 ohms the SWR rise to 1:1,1. Perfect!

The schematic diagram of preamplifier looks very simple – two LC circuits and MMIC. There is much more to do with adjusting bandpass filter and fiting the circuit in the shielted box and all in the waterproof box.

The circuit was later improved with a LED diode which is indicating if the current is flowing to the box or not. Output plug is standard PL.

Tags: preamplifier | beverage | antenna | ferrite cores | transformer | W8JI | schematic diagram